1. Field of the Invention
The present disclosure relates to a light source, a light source unit and a light source module having large optical output for use in a display such as a projector, welding and processing devices, and the like.
2. Description of the Related Art
A light source has been developed that radiates beams having very high energy whose optical output exceeds 1 watt. Particularly, the light source that efficiently radiates beams excellent in directivity has been considered in various applications. As the above-described light source that radiates the beams excellent in directivity, cited is a semiconductor light-emitting device represented by a semiconductor laser, in which a semiconductor light-emitting element with an optical waveguide is mounted on a package or the like. For example, an InAlGaP-based or InAlGaAs-based compound semiconductor or the like is used as a material of the semiconductor light-emitting element. The semiconductor light-emitting device using this semiconductor light-emitting element has been developed in applications of light sources of industrial processing devices such as a welding device, a processing device, a laser scribing device, a thin-film annealing device and the like, a long-wavelength light source of a display, and other light sources. Moreover, an InAlGaN-based nitride semiconductor or the like is used as the material of the semiconductor light-emitting element. The semiconductor light-emitting device using this semiconductor light-emitting element has been developed as a light source of an image display device such as a laser display and a projector, and a light source for an excitation light source unit of a white solid-state light source. For example, a light source module in which the light source as the semiconductor light-emitting device is used as an excitation light source to be combined with a phosphor can emit white light having high optical output. Thus, the development of the above-described light source module has been advanced for a projection type image display device such as a projector.
It is desirable that these light sources and the light source units radiate beams exceeding, for example, several ten watts as the optical output. Thus, for a structure to release heat generated in the light source, and a structure to efficiently radiate the beams radiated from the light source to an outside of an optical system, various contrivances are necessary.
With regards to the above-described problem, for example, Patent Literature 1 has proposed a structure of a light source unit in which a plurality of light sources are combined. Hereinafter, referring to FIG. 18, a conventional light source unit will be described. Light source unit 1000 is made up of light source group 1010 and first reflecting mirror group 1020 that is disposed on optical axes of light source group 1010. Light source group 1010 includes a plurality of light sources 1001 that are arrayed in a plane so as to form rows and columns. First reflecting mirror group 1020 reflects a bundle of rays emitted from light sources 1001 making up the respective rows of light source group 1010 as a bundle of rays whose cross-sectional area is reduced in the columnar direction by narrowing row intervals of the bundle of rays emitted from light sources 1001. Light sources 1001 are made up of a plurality of semiconductor laser elements 1005, and a plurality of collimator lenses 1007 that converts beams generated by the laser elements to parallel beams. First reflecting mirror group 1020 is made up by disposing, in a stepwise shape, strip-like reflecting mirrors 1025 different from one another on optical axes of the bundle of rays emitted as parallel beams from the respective rows of light source group 1010. Respective reflecting mirrors 1025 are disposed so as to reduce intervals between reflected beams from reflecting mirrors 1025, which can reduce the cross-sectional area of the bundle of rays. Moreover, since a plurality of luminous fluxes generated from the plurality of semiconductor laser elements 1005 are parallel to one another, they can be condensed by a small optical system to be used.